ICIC in DL and UL with network distributed and self-organized resource assignment algorithms in LTE

Inter-cell Interference coordination (ICIC) has gained much interest in the 3rd Generation Partnership Project's (3GPP's) Long Term Evolution (LTE) standardization of a new air interface. Due to the new physical layer, interference can now be predicted and avoided on a frequency basis. Such schemes are based on cell wise usage restrictions or resource preferences. After explaining the general degrees of freedom, we present an “inverted” reuse scheme for downlink and uplink and explain its advantages. This is supported by 3GPP-compliant system simulations. The question of assignment of restrictions or preferences naturally leads to a need for self-organization. For that, the concept of semi-static ICIC based on a request-grant mechanism applicable to load balancing is explained. For the static ICIC case with frequency planning, a novel and fully distributed algorithm provides optimized assignment of resource restrictions to the cells in a self-organizing way. It is capable of resolving sub-optimal aspects and comprises methods to detect and prevent possible system instabilities. The algorithms presented lead to an integrated ICIC-self-organizing network (SON) concept that can be realized in a multi-cell network solution.